Wildflower/Perennial
Black-eyed Susan
Rudbeckia hirta · Asteraceae
Also called: Gloriosa daisy, Brown-eyed Susan
Black-eyed Susan (Rudbeckia hirta) is a moderate-water wildflower/perennial well suited to Tucson and the low desert. It thrives in full sun.
Black-eyed Susan at a glance
- Water use
- Moderate (established)
- Sun
- Full sun; in Tucson's low desert benefits from light afternoon shade to reduce summer heat stress.
- Mature size
- 1-3 ft tall and 1-2 ft wide.
- Growth rate
- Fast.
- Bloom
- Golden-yellow rays with a dark brown/black central cone; some cultivars bronze, orange, or mahogany., Late spring through fall in Tucson; heaviest in spring and early summer, with a possible flush after monsoon rains.
- Cold hardiness
- Cold-hardy in USDA 9a-9b; tops may die back after hard frost but roots survive. Heat-stressed in peak summer without afternoon shade and water.
- Soil
- Adaptable; prefers well-drained loam with some organic matter. Tolerates Tucson's alkaline soils but appreciates amended beds.
- Native range
- Central and eastern North America (eastern U.S. prairies and meadows); not native to the Sonoran Desert.
- Best used as
- Pollinator garden, Cottage/wildflower beds, Cut flowers, Mass color plantings, Containers
- Wildlife
- Attracts bees, butterflies, and other pollinators; goldfinches and other birds eat the seeds.
- Toxicity
- Generally considered low toxicity, but foliage can cause skin/contact irritation in sensitive people and mild stomach upset if pets ingest large amounts. Not a serious hazard to kids or pets.
How to grow Black-eyed Susan in Tucson & the low desert
Watering
More water-needy than true desert plants. Water deeply 1-2 times per week in the warm season to keep soil from fully drying; reduce to every 10-14 days in winter. Mulch to conserve moisture.
Fertilizer & nutrients
Light feeder. Apply a balanced all-purpose fertilizer or compost once in spring; avoid excess nitrogen, which produces foliage at the expense of flowers.
Pruning & care
Deadhead spent flowers through the season to prolong bloom. Cut back tired stems in late fall or late winter. Often grown as a short-lived perennial or reseeding annual in the low desert.
Notes
Best treated as a spring/fall color plant in Tucson; it is not as drought-tough as desert perennials and will look ragged in mid-summer heat without afternoon shade and regular water. Many forms self-sow.
Sources: University of Arizona Cooperative Extension / Pima County Master Gardeners; Arizona-Sonora Desert Museum; USDA NRCS PLANTS Database